The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
An automatic transmission changes a gear ratio depending on a driving state of a vehicle to automatically perform a shift to a target shift stage.
When the shift to the target shift stage is performed, an off-coming friction element released in an operating state and an on-coming friction element changed from the releasing state to the operating state are present in the automatic transmission, and the releasing and the coupling of the off-going friction element and the on-coming friction element are performed by controlling an oil pressure supplied to each friction element. Further, the control of the oil pressure supplied to the off-coming friction element and the on-coming friction element is performed by operating a control duty to control a solenoid valve.
Generally, a shift control method uses slips of the off-coming friction element and the on-coming friction element to synchronize a speed of an input shaft of the automatic transmission with a speed of an output shaft thereof. However, a method for manually synchronizing a speed of an input shaft with a speed of an output shaft using a slip has a problem in that a shift time is long and shift quality is changed in response to a driving state (e.g., slope of a road, vehicle load, or the like).
Further, a hybrid vehicle does not use a torque converter for improvement in fuel efficiency, and therefore drivability of the hybrid vehicle may be adversely affected when the shift quality is not good.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the present disclosure and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art.